A deflection yoke is installed on the rear of the outer circumferential surface of the funnel of a color cathode ray tube. Electric field occurring to a vertical and horizontal deflection coil composing the deflection yoke moves and scans electron beams on a fluorescent screen of the colour cathode ray tube to form the picture. Accordingly, it is found to be important that picture quality depends on the precise position of the deflection yoke on the outer circumferential surface of the funnel of the color cathode ray tube. This precise position is determined by the yoke pull-back and the beam rotation. The yoke pull-back is to move the deflection yoke axially on the outer circumferential surface of the neck of a color cathode ray tube, resulting in controlling the static convergence and the purity. The beam rotation is to adjust the inclination of the deflection yoke mounted on the funnel and move it circumferentially around the outer circumferential surface of the neck, resulting in controlling the dynamic convergence.
FIG. 4 shows the conventional art which was to install a deflection yoke on the funnel of a color cathode ray tube. The deflection yoke was composed by separators. A separator S was provided with a vertical deflection coil V and a horizontal deflection coil H. The vertical deflection coil V was disposed on the outer circumferential surface, and the horizontal deflection coil H was disposed on the inner circumferential surface perpendicularly to this vertical deflection coil. This separator S was inserted on the neck N of the cathode ray tube C and thus secured by a clamp R. Conventionally, the deflection yoke involved the following process. Before clamping, the yoke pull-back was done and concurrently, the deflection yoke was slowly rotated around the outer circumferential surface of the neck, resulting in controlling most appropriately the beam rotation. Then, the clamp R secures it on the neck portion. After clamping, wedges W lay between the funnel of the cathode ray tube C and the deflection yoke, resulting in correcting the inclination of the deflection yoke. However, since the yoke pull-back and the beam rotation were done without other tools, while the yoke pull-back was being, the beam rotation may go awry or while the beam rotation was being, the yoke pull-back may go awry. Furthermore, once the deflection yoke was permanently attached on the cathode ray tube C by adhesive and wedge, if a poor quality product occurring due to improperly installing the deflection yoke is discovered, the adhesive (silicon bond) and wedge should be inconveniently melted again in order to correct the installation of the deflection yoke.
It has been known that the method for solving these problems occurring in the assembly of a deflection yoke was introduced on the Japanese Patent Publication No. Sho 61-7703 of Mar. 8, 1986. The deflection yoke proposed therefrom comprised a cone part and a neck holder part. The cone part comprised a vertical deflection coil and a horizontal deflection coil. The neck holder part was connected to the outer circumferential surface of the neck by a clamp. However, even though the clamp tightened the neck holder up the neck of a CRT, the cone part could freely solely rotate on the outer circumferential surface of the funnel of the cathode ray tube. This structure was very convenient by reason that the yoke pull-back was done, the clamp tightened the neck holder and the beam rotation was done, resulting in the simple job and obtaining the precise position.
However, since the relative adjustment of the neck holder part against the cone part depends on the frictional contact, there can be problems such that the structure of the deflection yoke can be complicated and the elements used are increased due to the additional final fixing tools such as bolts, nuts, and locking rings.